2015年3月磁暴期间中国中低纬地区电离层变化分析

2015年3月17日爆发了本太阳活动周最大的地磁暴,Dst指数达到-233 nT.本文利用电离层测高仪f_。F_2和h_mF_2、北斗同步卫星(BDSGEO)TEC以及GPS电离层闪烁S4指数对此次磁暴期间中国中低纬地区(北京、武汉、邵阳和三亚)的电离层变化进行分析,并对此次磁暴所引发电离层暴的可能机制进行了探讨.磁暴期间,中低纬电离层暴整体表现为正相暴之后长时间强的负相暴.3月17日白天中纬正相暴为风场抬升电离层所致,而驼峰区及低纬地区正相暴由东向穿透电场所引起;3月18日白天长时间的强负相暴为西向扰动发电机电场和成分扰动所引起;3月17和18日夜间的负相暴可能是日落东向电场受到抑制以及赤道向风场对扩散的抑制导致驼峰向赤道压缩所致,同时被抑制的日落东向电场强度不足以触发产生赤道扩展F,导致低纬三亚和邵阳夜间电离层闪烁在磁暴期间受到完全抑制.这是我们首次基于北斗同步卫星TEC组网观测开展的电离层暴研究.

Analysis of ionospheric features in middle and low latitude region of China during the geomagnetic storm in March 2015

The strongest geomagnetic storm of the current solar cycle occurred on 17 March 2015, with a minimum Dst index of -233 nT. In this paper, we reported the ionospheric disturbances in the middle and low latitude region of China during this storm. Here we utilized ionosondes data (f_oF₂ and h_mF₂) and BDS GEO TEC from our 4 stations in Beijing, Wuhan, Shaoyang and Sanya, along with GPS S4 index. Possible mechanisms responsible for the ionospheric disturbances characterized by a positive storm followed by a long duration strong negative storm were discussed. Observations and analysis showed that during the daytime of March 17, the positive storm in the middle latitude was caused by neutral wind which uplifted the ionosphere, while the positive storm in the low latitude and near the northern equatorial ionization anomaly (EIA) was mainly caused by eastward prompt penetration electric field (PPEF). The long-lasting negative storm during the daytime of March 18 was due to westward disturbance dynamo electric field (DDEF) as well as neutral composition disturbances. During the nighttime of March 17 and 18, the negative storm and the absence of spread-F and ionospheric scintillation could be caused by the suppression of eastward electric field after the sunset and the equatorward wind surge, which pushed the EIA towards the equator. This was the first research related to ionospheric storm based on BDS GEO TEC network.